Tuesday, December 11, 2012

NOAA 2012 report finds sea levels rising at less than half the rate claimed by the IPCC

According to the latest NOAA sea level budget, global sea levels rose at only 1.1 - 1.3 mm/year from 2005-2012, which is less than half of the rate claimed by the IPCC [3.1 mm/yr] and is equivalent to less than 5 inches per century. Contrary to alarmist claims, sea level rise decelerated over the 20th century, has also decelerated since 2005, and there is no evidence of any human influence on sea levels.The report compares sea-level rise calculated from two different methods: 1) satellite altimetry and 2) ARGO measurements of the steric [thermal expansion] component + GRACE measurements of ocean mass. The rate of sea level rise using the 2nd method [ARGO + GRACE] shows a sea level rise of only 0.2 {ARGO] + 0.1 [GRACE] = 0.3 mm/yr. Only by adding on a relatively large and highly questionable GIA adjustment [based on a model] of 0.9 mm/yr to the GRACE data do the two estimates come close to agreement. Following this questionable GIA adjustment, the ARGO + GRACE estimate is 1.1± 0.8 mm/yr as compared to the satellite altimetry estimate of 1.3 ± 0.9 mm.

This table apparently has a typo since the text reports Total sea level change [Jason 1 & 2] is 1.3± 0.9 mm/yr

Satellite measurements of Earth’s time-varying gravity field provided by GRACE are used to infer movement of water mass over Earth’s surface. We use Release-04 gravity field solutions from the University of Texas Center for Space Research. GRACE does not observe geocenter variations and current GRACE solutions for oblateness variations may be less accurate than satellite laser ranging (SLR) estimates [Chen and Wilson, 2008]. Therefore, we compute ocean mass variations by replacing the degree 2, order 0 coefficients with those from an SLR analysis [Cheng and Tapley, 2004] and adding an estimate of seasonal geocenter motion [Chen et al., 1999] to account for the degree 1 components of the gravity field. Recent estimates based on ocean models and GRACE fields over land suggest that trends in ocean mass from geocenter variations are on the order of a few tenths of a mm/a [Swenson et al., 2008]. We restore the atmosphere and ocean models removed from the gravity field prior to processing. To compute the equivalent sea level of ocean mass variations that can be compared to SLtotal as measured by altimetry with an inverse barometer applied, we remove the time-varying mass of the atmosphere averaged over the global ocean.

Secular geoid variations over the ocean that result from GIA must be removed from gravity observations to isolate ocean mass variations. We apply a model [Paulson et al., 2007] that effectively increases the trend in observed SLmass by 0.9 mm/a. The ice history (ICE-5G) used to produce the GIA model has an estimated uncertainty of roughly 20%. An averaging function is applied to the GRACE fields that restricts our analysis to the latitudes covered by Jason-1 (± 66°) and excludes regions within 300 km of the continental coastlines.
Mass variations in the ocean estimated from satellite gravity observations are vulnerable to leakage of gravity signals from land hydrology. Chambers et al. [2007] suggest that this could cause the secular trend in ocean mass to be underestimated by 0.17 ± 0.08 mm/a. To minimize the sum of the variance from GRACE errors and the variance of signals outside the ocean, we apply a 300-km Gaussian averaging kernel [Wahr et al., 1998]. Errors in the estimated monthly mass component of the global mean sea level are 2 mm for each month [Willis et al., 2008].

2 Sea level budget

Trends and seasonal terms for SLmass, SLsteric, and, SLtotal are determined with a least squares fit of
a sine, cosine, trend, and constant over January 2005 to December 2011. No smoothing was performed on the time series. The Argo and GRACE time series are monthly observations (N = 84). Errors in Table 1 are estimated from the least squares fit, where we have assumed that each sample is an independent measurement.
In this analysis, the global sea level rise budget for 2005–2012 is closed when the Paulson GIA correction is applied (Table 1). The sum of steric sea level rise and the ocean mass component has a trend of 1.1 ± 0.8 mm/a over the period when the Paulson GIA mass correction is applied, well overlapping total sea level rise observed by Jason-1 and Jason-2 (1.3 ± 0.9 mm/a) within a 95% confidence interval.

The above numbers represent the globally averaged changes in sea level and have magnitudes on the order of millimeters per year. The regional patterns of sea level change, however, are many times larger and can be extremely complex. Steric sea level change is the dominant contributor to the spatial trend patterns observed for total sea level (Figure 3). While the global ocean has been gaining mass from the continents during this period, the Indian Ocean continues to show a net loss of mass to the other basins (Chambers and Willis 2009).

7 comments:

I think that the difference between the 1.3mm/year and the 1.6mm/year is the estimated 0.3mm/year isostatic sinking of the ocean floor that is thought to be a response to the end of the last glaciation adding to the mass of the oceans.

Of course, whenever you are splitting hairs over fractions of a millimeter per year, you have to remember how insignificant it is in the real world.

The IPCC predictions are wrong because the models are wrong. The models (and typical explanations of the so-called greenhouse conjecture) all assume implicitly that there would have been a zero thermal gradient in the atmosphere in the absence of radiating molecules. This flies in the face of physics that dates back to the late 19th century when Loschmidt said he believed there would be a natural temperature gradient in still air which was in a gravitational field. This was due to a molecular process which, by keeping the sum of KE+PE constant, ensures entropy does not decrease, for the laws of physics say it never does.

But the IPCC assumptions implicitly depend upon such a violation of one of the most basic laws of physics known to mankind.

Does anybody know how much the crustal uplift of glaciated areas like NW Europe and Canada plus the possible role of plate tectonics, sea floor adjustments and erosion on land an ddepositon along the continental margins?